1. Field of the Invention
The present invention relates to a navigation control system for an automotive vehicle and, more particularly, to a navigation control system for an automotive vehicle, having a deviation suppressing means so adapted as to return the vehicle to its original lane on which the vehicle is running, when the vehicle has been deviated from its original lane, or as to allow the vehicle to hold its original or current lane when it is deviating therefrom.
2. Description of the Related Art
Heretofore, automotive vehicles have been equipped with seat belts and air bags in order to ensure safety of passengers. Further, devices for preventing an accident from occurring have been developed. As described in Japanese Patent Laid-open Publication (kokai) No. 63214,900, for example, it is known a device for giving an alarm to the operator when the automotive vehicle has been deviated from its given lane without steering which is effected under conscious control by the operator.
Further, Japanese Patent Laid-open Publication (kokai) No. 2-270,005 discloses a navigation control system having an image pick-up unit for reading a guide line partitioning lanes of a road, such as a center line, a white line or the like, and an image processing unit for processing signals from the image pick-up unit, the navigation control system being adapted to control the body of the automotive vehicle so as to run in a given position on the lane of the road defined and delimited between the guide lines indicated on the road.
These conventional techniques, however, do not take into account the timing of operating the action to hold the vehicle at its original lane or to return the vehicle to its original lane, when the vehicle running on the lane has gone beyond one of the guide lines on the lane and deviated from the lane into the adjacent lane or when it is going or about to go beyond the adjacent guide line. Hence, for instance, if the navigation control system as described in Japanese Patent Laid-open Publication No. 2-27,000 would be so arranged as to uniformly operate the action for correcting the steering of the vehicle at an earlier timing, it is preferred that the situation in which the vehicle is deviating from the current lane can be suppressed, whereas it is disadvantageous that the early timing of operating the action to correct the steering of the vehicle may give rise to a feeling of unpleasantness because the action to correct the steering of the vehicle should be carried out at a high frequency. On the other hand, if the action to correct the steering of the vehicle is to be uniformly carried out at a later timing, the conventional navigation control system suffers from the disadvantage that the action of the vehicle to deviate from the lane on which the vehicle is running cannot be suppressed to a sufficient extent, although a frequency of operating the action to correct the steering of the vehicle is reduced to thereby ensure a feeling of comfortableness.